Add example for custom fast Accesslog Formatter

_examples/README.md

@@ -71,16 +71,17 @@
     * [API Versioning](routing/versioning/main.go)
     * [Sitemap](routing/sitemap/main.go)
 * Logging
-    * [Request Logger](logging/request-logger/main.go)
-        * [AccessLog: simple example](logging/request-logger/accesslog-simple/main.go)
-        * [AccessLog: log request & response and more](logging/request-logger/accesslog)
-        * [AccessLog: custom fields and template](logging/request-logger/accesslog-template/main.go)
-        * [AccessLog: CSV Format](logging/request-logger/accesslog-csv/main.go)
-        * [AccessLog: listen to logs and render them](logging/request-logger/accesslog-broker/main.go)
-        * [Log Requests to a JSON File](logging/request-logger/request-logger-file-json/main.go) 
     * [Application File Logger](logging/file-logger/main.go)
     * [Application JSON Logger](logging/json-logger/main.go)
     * [Rollbar](logging/rollbar/main.go)
+    * AccessLog
+        * [Log Requests to a JSON File](logging/request-logger/accesslog-simple/main.go)
+        * [Using Log Rotation and more](logging/request-logger/accesslog)
+        * [Custom Fields and Template](logging/request-logger/accesslog-template/main.go)
+        * [Listen and render Logs to a Client](logging/request-logger/accesslog-broker/main.go)
+        * [The CSV Formatter](logging/request-logger/accesslog-csv/main.go)
+        * [Create your own Formatter](logging/request-logger/accesslog-formatter/main.go)
+        <!-- * [Log Requests to a JSON File](logging/request-logger/request-logger-file-json/main.go)  -->
 * API Documentation
     * [Yaag](apidoc/yaag/main.go)
     * [Swagger](https://github.com/iris-contrib/swagger/tree/master/example)

_examples/logging/request-logger/accesslog-formatter/main.go

@@ -0,0 +1,129 @@
+// Package main shows to create a quite fast custom Log Formatter.
+// Note that, this example requires a little more knowledge about Go.
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"strconv"
+	"sync"
+	"time"
+
+	"github.com/kataras/iris/v12"
+	"github.com/kataras/iris/v12/middleware/accesslog"
+	"github.com/kataras/iris/v12/middleware/requestid"
+)
+
+func logFields(ctx iris.Context, fields *accesslog.Fields) {
+	fields.Set("reqid", ctx.GetID())
+}
+
+func main() {
+	app := iris.New()
+
+	ac := accesslog.File("./access.log").
+		AddFields(logFields).
+		SetFormatter(newCustomFormatter(' ', "-\t\t\t\t\t"))
+	ac.RequestBody = false
+	ac.BytesReceivedBody = false
+	ac.BytesSentBody = false
+	defer ac.Close()
+
+	app.UseRouter(ac.Handler)
+	app.UseRouter(requestid.New())
+
+	app.OnErrorCode(iris.StatusNotFound, notFound)
+	app.Get("/", index)
+
+	app.Listen(":8080")
+}
+
+func notFound(ctx iris.Context) {
+	ctx.WriteString("The page you're looking for does not exist!")
+}
+
+func index(ctx iris.Context) {
+	ctx.WriteString("OK Index")
+}
+
+type customFormatter struct {
+	w       io.Writer
+	bufPool *sync.Pool
+
+	delim byte
+	blank string
+}
+
+var _ accesslog.Formatter = (*customFormatter)(nil)
+
+func newCustomFormatter(delim byte, blank string) *customFormatter {
+	return &customFormatter{delim: delim, blank: blank}
+}
+
+func (f *customFormatter) SetOutput(dest io.Writer) {
+	f.w = dest
+	f.bufPool = &sync.Pool{
+		New: func() interface{} {
+			return new(bytes.Buffer)
+		},
+	}
+
+	if f.delim == 0 {
+		f.delim = ' '
+	}
+}
+
+const newLine = '\n'
+
+func (f *customFormatter) Format(log *accesslog.Log) (bool, error) {
+	buf := f.bufPool.Get().(*bytes.Buffer)
+
+	buf.WriteString(log.Now.Format(log.TimeFormat))
+	buf.WriteByte(f.delim)
+
+	reqid := log.Fields.GetString("reqid")
+	f.writeTextOrBlank(buf, reqid)
+
+	buf.WriteString(uniformDuration(log.Latency))
+	buf.WriteByte(f.delim)
+
+	buf.WriteString(log.IP)
+	buf.WriteByte(f.delim)
+
+	buf.WriteString(strconv.Itoa(log.Code))
+	buf.WriteByte(f.delim)
+
+	buf.WriteString(log.Method)
+	buf.WriteByte(f.delim)
+
+	buf.WriteString(log.Path)
+
+	buf.WriteByte(newLine)
+
+	// _, err := buf.WriteTo(f.w)
+	// or (to make sure that it resets on errors too):
+	_, err := f.w.Write(buf.Bytes())
+	buf.Reset()
+	f.bufPool.Put(buf)
+
+	return true, err
+}
+
+func (f *customFormatter) writeTextOrBlank(buf *bytes.Buffer, s string) {
+	if len(s) == 0 {
+		if len(f.blank) == 0 {
+			return
+		}
+
+		buf.WriteString(f.blank)
+	} else {
+		buf.WriteString(s)
+	}
+
+	buf.WriteByte(f.delim)
+}
+
+func uniformDuration(t time.Duration) string {
+	return fmt.Sprintf("%*s", 12, t.String())
+}

middleware/accesslog/accesslog.go

@@ -631,7 +631,7 @@ func (ac *AccessLog) after(ctx *context.Context, lat time.Duration, method, path
 			requestData, err := ctx.GetBody()
 			requestBodyLength := len(requestData)
 			if ac.BytesReceivedBody {
-				bytesReceived = requestBodyLength // store it, if the total is enabled then this will be overriden.
+				bytesReceived = requestBodyLength // store it, if the total is enabled then this will be overridden.
 			}
 			if err != nil && ac.RequestBody {
 				requestBody = ac.getErrorText(err)